Dynamic simulation of constrained multibody systems with electromechanical actuators using a monolithic approach

Electromechanical actuators (EMAs) are becoming increasingly attractive across industries such as aviation, automotive, robotics, and heavy machinery, due to their precise motion control, high efficiency, reliability, and seamless integration with electronic control systems. Mobile machinery has traditionally relied on hydraulic actuators for their high power density and robustness. However, hydraulic systems suffer from drawbacks including fluid leakage, environmental hazards from oil contamination, and poor energy efficiency and electronic integration. Growing environmental concerns have intensified the interest in electrification alternatives. This paper presents a novel monolithic approach for dynamic simulation of constrained multibody systems driven by EMAs. The framework integrates the governing equations of the mechanical and electrical subsystems into a unified, coupled system, achieving accurate and efficient simulations. The EMA subsystem employs a Permanent Magnet Synchronous Motor (PMSM) model driven by Field-Oriented Control (FOC). The main contributions of this work are the development of the monolithic approach and the detailed description of the coupling between the mechanical and electrical subsystems. A comparison with an existing hydraulics-based monolithic approach is also included. The method is demonstrated through numerical simulations of a log crane multibody model with two EMAs and can be systematically applied to other EMA-actuated multibody systems. The proposed methodology supports design optimization by evaluating EMA configurations, predicting energy consumption across machinery work cycles, and preliminarily sizing EMA components such as electric motors based on power demands. It also facilitates comparisons between EMAs and hydraulic actuators, advancing the electrification roadmap.